The 212 decoders are a seriesofCMOS LSIs for remote control system applications. They arepairedwith Holtek's 212 series of encoders (refer totheencoder/decoder cross reference table). For proper operation,apair of encoder/decoder with the same number of addresses anddataformat should be chosen.

The decoders receive serial addressesanddata from a programmed 212 series of encoders thataretransmitted by a carrier using an RF or an IR transmissionmedium.They compare the serial input data three times continuouslywiththeir local addresses. If no error or unmatched codes arefound,the input data codes are decoded and then transferred to theoutputpins. The VT pin also goes high to indicate a validtransmission.

The 212 series of decodersarecapable of decoding informations that consist of N bits ofaddressand 12-N bits of data. Of this series, the HT12D is arrangedtoprovide 8 address bits and 4 data bits, and HT12F is used todecode12 bits of address information.